sinI- andexpR-Dependent Quorum Sensing inSinorhizobium meliloti

Gao, Mengsheng; Chen, Hancai; Eberhard, Anatol; Gronquist, Matthew R.; Robinson, Jayne B.; Rolfe, Barry G.; Bauer, Wolfgang

doi:10.1128/jb.187.23.7931-7944.2005

Cited by 83 publications

(112 citation statements)

References 79 publications

(119 reference statements)

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“…One is a surface-swarming motion of hyperflagellated cells, described in detail by Soto et al [6]. The other is an unusual type of surface spreading or translocation that has been observed by several groups [5,6,9] and was recently described in detail by Gao et al [8] and Nogales et al [7]. A newly inoculated colony that spreads by this mechanism first acquires a wet appearance as it secretes a nearly transparent mucoid fluid or slime.…”

Section: Introductionmentioning

confidence: 99%

“…The cells travel outward with the mucoid layer until the colony is dispersed over a final area as large as approximately 1 cm 2 . During this spreading, the colony typically develops a feathered or curdled, patterned appearance as shown in figure 1 and in the images in references [7][8][9]. The mechanism of this spreading has been unclear.…”

Section: Introductionmentioning

confidence: 99%

“…Sinorhizobium meliloti is capable of at least two forms of motility on semi-solid agar surfaces [5][6][7][8][9]. One is a surface-swarming motion of hyperflagellated cells, described in detail by Soto et al [6].…”

Section: Introductionmentioning

confidence: 99%

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Entropy-driven motility of Sinorhizobium meliloti on a semi-solid surface

2014

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Sinorhizobium meliloti growing on soft agar can exhibit an unusual surface spreading behaviour that differs from other bacterial surface motilities. Bacteria in the colony secrete an exopolysaccharide-rich mucoid fluid that expands outward on the surface, carrying within it a suspension of actively dividing cells. The moving slime disperses the cells in complex and dynamic patterns indicative of simultaneous bacterial growth, swimming and aggregation. We find that while flagellar swimming is required to maintain the cells in suspension, the spreading and the associated pattern formation are primarily driven by the secreted exopolysaccharide EPS II, which creates two entropy-increasing effects: an osmotic flow of water from the agar to the mucoid fluid and a crowding or depletion attraction between the cells. Activation of these physical/chemical phenomena may be a useful function for the high molecular weight EPS II, a galactoglucan whose biosynthesis is tightly regulated by the ExpR/SinI/SinR quorum-sensing system: unlike bacterial colonies that spread via bacterium-generated, physical propulsive forces, S. meliloti under quorum conditions may use EPS II to activate purely entropic forces within its environment, so that it can disperse by passively 'surfing' on those forces.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Entropy-driven motility of Sinorhizobium meliloti on a semi-solid surface

2014

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“…These QSS also govern motility and exopolysaccharide production which is required for infection process, and biofilm formation [80,81]. In Sinorhizobium meliloti, sinI/ sinR and expR, regulate the Sin QSS through long chain AHLs: C12HSL to C18HSL [29,[82][83][84]. The phenotypes thus controlled by QSS are nodule formation swarming, motility, and chemotaxis ( Table 2).…”

Section: Rhizobiummentioning

confidence: 99%

Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria

et al. 2015

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Expression of certain bacterial genes only at a high bacterial cell density is termed as quorum-sensing (QS). Here bacteria use signaling molecules to communicate among themselves. QS mediated genes are generally involved in the expression of phenotypes such as bioluminescence, biofilm formation, competence, nodulation, and virulence. QS systems (QSS) vary from a single in Vibrio spp. to multiple in Pseudomonas and Sinorhizobium species. The complexity of QSS is further enhanced by the multiplicity of signals: (1) peptides, (2) acyl-homoserine lactones, (3) diketopiperazines. To counteract this pathogenic behaviour, a wide range of bioactive molecules acting as QS inhibitors (QSIs) have been elucidated. Unlike antibiotics, QSIs don't kill bacteria and act at much lower concentration than those of antibiotics. Bacterial ability to evolve resistance against multiple drugs has cautioned researchers to develop QSIs which may not generate undue pressure on bacteria to develop resistance against them. In this paper, we have discussed the implications of the diversity and multiplicity of QSS, in acting as an arsenal to withstand attack from QSIs and may use these as reservoirs to develop multi-QSI resistance.

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“…It has also to be noted that S. meliloti is motile mainly in exponential phase, and its motility progressively decreases in stationary phase, in response to cell density (145). Actually, the ExpR/Sin and ExoR/ExoS/ChvI quorum sensing systems regulate both motility and EPS production as a well as a number of other functions according to the growth phase (146)(147)(148)(149)(150)(151). However, it is important to highlight that ExpR/Sin abolishes the repression of MucR on galactoglucan biosynthesis but does not affect the role of MucR on a number of other functions that promote symbiosis, such as repression of motility and increase in EPS I and Nod factors production (137).…”

Section: Regulation Of Mucoidy and Cell Densitymentioning

confidence: 99%

Developmental and environmental regulatory pathways in alpha-proteobacteria

Ardissone

Viollier²

2012

Front Biosci

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Spatial and temporal control of cell differentiation and morphogenesis plays a key role in prokaryotes as well as eukaryotes. This is particularly important for bacteria that divide asymmetrically, as they generate two morphologically and functionally distinct daughter cells. Several alpha-proteobacteria, including the aquatic, free-living Caulobacter crescentus, the symbiotic rhizobia and the plant and animal pathogens Agrobacterium and Brucella, have been shown to undergo asymmetrical division. C. crescentus has become a model system for the study of the regulatory networks, in particular the control of the cell cycle, the cytokinetic machinery, the cytoskeleton and the functions required for duplication and differentiation in general. As the bulk of these regulatory networks and functions is conserved in most alpha-proteobacteria, we recapitulate the recent advances in understanding these spatially and temporally controlled processes, focusing on cell cycle progression, DNA replication and partitioning, cell division and regulation of specific phenotypes that vary during the cell cycle or in the case of different lifestyles (like extracellular polysaccharide production) in C. crescentus and other alpha-proteobacteria

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sinI- andexpR-Dependent Quorum Sensing inSinorhizobium meliloti

Abstract: Quorum sensing (QS) in

Cited by 83 publications

References 79 publications

Entropy-driven motility of Sinorhizobium meliloti on a semi-solid surface

Entropy-driven motility of Sinorhizobium meliloti on a semi-solid surface

Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria

Developmental and environmental regulatory pathways in alpha-proteobacteria

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